Question: Solve for $x$ and $y$ using substitution. ${-x+2y = -9}$ ${y = x-5}$
Since $y$ has already been solved for, substitute $x-5$ for $y$ in the first equation. ${-x + 2}{(x-5)}{= -9}$ Simplify and solve for $x$ $-x+2x - 10 = -9$ $x-10 = -9$ $x-10{+10} = -9{+10}$ ${x = 1}$ Now that you know ${x = 1}$ , plug it back into $\thinspace {y = x-5}\thinspace$ to find $y$ ${y = }{(1)}{ - 5}$ $y = -4$ You can also plug ${x = 1}$ into $\thinspace {-x+2y = -9}\thinspace$ and get the same answer for $y$ : ${-}{(1)}{ + 2y = -9}$ ${y = -4}$